Laser illuminated backlight for flat panel displays

ABSTRACT

Laser lit flat panel displays are disclosed including edge-lit and direct lit backlights. In certain embodiments, laser assemblies are selected to obtain bandwidth distributions to reduce speckle.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser.No. 61/000,475, filed Oct. 26, 2007, the entire contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

Red, green, and blue (RGB) lasers offer demonstrable benefits overfluorescent lamps and light emitting diodes for high-performance imagingapplications. Greater color saturation, contrast, sharpness, andcolor-gamut are among the most compelling attributes distinguishinglaser displays from conventional imaging systems.

To compare laser illumination technology with conventional technologies,it is instructive to examine two fundamental parameters which relate totheir ultimate practicality. The first parameter can be defined asoptical efficiency—in this case, the lumens of output per watt of inputto the light source. The second is cost compatibility, that is, theextent to which the technology in question yields a cost effectivesolution to the requirements of a specific application.

Based on these parameters, a red/green/blue (RGB)semiconductor/microlaser system, consisting of three lasers or laserarrays, each operating at a fundamental color, appears to be the mostefficient, high brightness, white light source for display applicationsto date. Semiconductor laser operation has been achieved from the UV tothe IR range of the spectrum, using device structures based on InGaAlN,InGaAlP and InGaAlAs material systems. Desirable center wavelengthranges are 610-635 nm for red, 525-540 nm for green, and 445-470 nm forblue.

Laser radiation is inherently narrow band and gives rise to theperception of fully-saturated colors. Unfortunately, narrow band lightincident on random rough surfaces also introduces an unacceptable imageartifact known as “speckle”. The visual effects of speckle detract fromthe aesthetic quality of an image and also result in a reduction ofimage resolution. Consequently, in the context of high resolutiondisplay systems, it is generally deemed essential that speckle beeliminated. A variety of “de-speckling” techniques can be used to reducethis artifact to “acceptable levels”, but only at the expense of afurther loss in efficiency, which negatively impacts cost, reliability,package size, and power consumption.

Known speckle reduction techniques tend to disturb the spatial ortemporal coherence of laser beams through optical path randomizationand/or spectral broadening. However, most of these solutions areexpensive and technically complex, relying, for example, on mode-lockingtechniques to produce very short pulses in the order of 1 ps to increasethe optical bandwidth. Ideally, the spectral bandwidth for a displaylight source should be on the order of several nanometers (i.e., 5-15nm). Such a light source could be consideredquasi-monochromatic-sufficiently broadband for the cancellation ofspeckle yet sufficiently narrow band for color purity.

SUMMARY OF THE INVENTION

The invention is directed to a laser-lit display system which uses abandwidth-enhancing technique for reducing speckle.

According to one aspect of the invention, a laser-lit flat panel displayincludes a backlight with a plurality of lasing elements of at least twoprimary colors arranged in a plurality of laser assemblies. Theplurality of lasing elements of at least one of the three primary colorsare selected such that each lasing element emits a laser beam with acenter wavelength λ_(0i) and a spectral bandwidth Δλ_(i). The centerwavelength of at least one of the lasing elements is wavelength-shiftedwith respect to the center wavelength of at least one other lasingelement. When combined, the laser beams have an ensemble spectrum Λ withan overlap parameter γ= Δλ_(i) / S_(i) , where Δλ_(i) is a mean spectralbandwidth of the lasing elements and S_(i) is a mean wavelength shiftbetween the center wavelengths λ_(0i) of the at least one and the atleast one other lasing elements. Ideally, Δλ_(i) and S_(i) are selectedsuch that γ≧1. The laser-lit flat panel display also includes an arrayof light modulators arranged across the display for modulating lightemitted by the backlight.

In one embodiment, each laser assembly in the flat panel displayincludes at least one lasing element of each primary color. At least onelaser assembly includes a plurality of lasing elements of at least oneprimary color. A light guide in the backlight substantially distributesthe light output by the laser assemblies across the flat panel display,aided by diffusion optics corresponding to the laser assemblies. Lightemitted by the backlight is modulated by a liquid crystal display (LCD)panel.

The plurality of lasers in the flat panel display are positioned aboutan exterior edge of the light guide. For example, the plurality oflasers can be positioned about each exterior edge of the light guide orat corners of the light guide.

In one embodiment of the invention, the plurality of laser assembliesare arranged about the light guide in a plurality of rows. Each row oflaser assemblies is configured for independent control with respect tolaser assemblies in at least one other row. The laser assemblies arealso configured such that the brightness of at least one color within atleast one laser assembly can be controlled independently of other colorsin the laser assembly. The flat panel display has a plurality ofadditional light guides, each of which corresponds to a row of laserassemblies and is separated from adjacent light guides by a reflectiveseparator.

In another embodiment, the plurality of laser assemblies of thebacklight are configured to directly illuminate the array of lightmodulators from behind with the aid of diffusion optics corresponding tothe plurality of laser assemblies. The laser assemblies are arranged inan array behind the array of light modulators, and each laser assemblyis configured to be controlled independently of at least one laserassembly in the same row and at least one laser assembly in the samecolumn as the laser assembly. Each laser assembly includes at least onelasing element of each of the at least two primary colors. At least onelaser assembly is configured such that the brightness of one color oflaser is controllable independently of lasers of other colors in theassembly.

According to another aspect of the invention, a flat panel displayincludes a backlight with a plurality of lasing elements of at least twoprimary colors arranged in an array of laser assemblies. The displayalso includes an array of light modulators directly illuminated frombehind by the plurality of laser assemblies and a plurality of opticalelements for diffusing light from the laser assemblies acrosscorresponding regions of the array of light modulators.

In one embodiment, each laser assembly in the display includes at leastone lasing element of each of the at least two primary colors. Eachlaser assembly is configured to be controlled independently of at leastone laser assembly in the same row and at least one laser assembly inthe same column as the laser assembly. The laser assemblies are alsoconfigured such that the brightness of at least one color within eachlaser assembly can be controlled independently of other colors in thelaser assembly.

Further features and advantages of the present invention will beapparent from the following description of preferred embodiments andfrom the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The following figures depict certain illustrative embodiments of theinvention in which like reference numerals refer to like elements. Thesedepicted embodiments are to be understood as illustrative of theinvention and not as limiting in any way.

FIG. 1 shows schematically the layers of a liquid crystal display (LCD)screen;

FIG. 2A shows schematically the spectral emission and the ensemblespectrum of five exemplary lasing elements having a mean spectraloverlap parameter γ>1;

FIG. 2B shows schematically the spectral emission and the ensemblespectrum of five exemplary lasing elements having a mean spectraloverlap parameter γ=1;

FIG. 3 shows schematically an illustrative configuration for alaser-illuminated backlight for a liquid crystal flat panel displayaccording to an illustrative embodiment of the invention;

FIG. 4A shows schematically a second illustrative configuration for alaser-illuminated backlight for a liquid crystal flat panel displayaccording to an illustrative embodiment of the invention;

FIG. 4B shows schematically a third illustrative configuration for alaser-illuminated backlight for a liquid crystal flat panel displayaccording to an illustrative embodiment of the invention;

FIG. 4C shows schematically a fourth illustrative configuration for alaser-illuminated backlight for a liquid crystal flat panel displayaccording to an illustrative embodiment of the invention;

FIG. 5A shows schematically an illustrative configuration of a laserassembly for illuminating a liquid crystal display;

FIG. 5B shows schematically a second illustrative configuration of alaser assembly for illuminating a liquid crystal display;

FIG. 6 shows schematically an illustrative configuration forarea-dimming control on an edge-lit backlight for a liquid crystaldisplay.

FIG. 7 shows schematically a laser-illuminated backlight for a liquidcrystal flat panel display in an alternative illustrative embodiment ofthe invention.

DETAILED DESCRIPTION OF CERTAIN ILLUSTRATED EMBODIMENTS

To provide an overall understanding of the invention, certainillustrative embodiments will now be described, including abandwidth-enhanced laser light source for flat-panel displays, such asliquid crystal displays (LCDs). However, it will be understood by one ofordinary skill in the art that the apparatus described herein may beadapted and modified as is appropriate for the application beingaddressed and that the systems and methods described herein may beemployed in other suitable applications, and that such other additionsand modifications will not depart from the scope hereof.

FIG. 1 shows schematically the layers of a liquid crystal display (LCD)screen 100, according to an illustrative embodiment of the invention. Atthe back is a reflector 102 for directing light toward the front of thedisplay. Light from the reflector passes through a light guide 104,usually made of molded transparent or white plastic. In oneimplementation, the light guide 104 has a plurality of microlensesmolded into its surface to aid in extracting light at predeterminedpoints. Suitable light guides can be obtained, for example, from GlobalLighting Technologies (headquartered in Brecksville, Ohio). Positionedadjacent to the light guide 104 are laser assemblies 106, which providelight for the display. The laser assemblies 106 emit light into thelight guide, which then distributes the light across the display. Thelight guide also serves to mix the light from the various laserassemblies to achieve a generally white light source. The laserassemblies, described further below in relation to FIGS. 5A and 5B, maybe arranged around the light guide in various configurations, asdescribed in relation to FIGS. 3-4. From the light guide 104, lightpasses through a diffuser sheet 108, which further diffuses light acrossthe display. In front of the diffuser sheet 108 are two optical films, abrightness enhancing film 110 for directing light toward the viewer (forexample, BEF II-T, which can be obtained under the brand name Vikuitifrom 3M, headquartered in St. Paul, Minn.), and a polarizing film 112(for example, DBEF II, which can also be obtained from 3M under thebrand name Vikuiti). After being polarized, light extracted from thelight guide 104 illuminates an LCD panel 114. LCD panels can beobtained, for example, from Sharp (headquartered in Osaka, Japan) andSamsung (headquartered in Seoul, Korea).

As mentioned above, laser illumination typically results in imagespeckle. However, as disclosed in U.S. Pat. No. 6,975,294, entitledSystems and Methods for Speckle Reduction through Bandwidth Enhancement,laser light sources formed from multiple lasers with certain frequencyand bandwidth characteristics reduce if not eliminate speckle. Thecritical parameters for designing a bandwidth-enhanced laser array(BELA) include the number n of emitters in the array, the centerwavelength λ_(0i) of each emitter, the spectral separation S_(i) betweenthe center wavelength λ_(0i) of an emitter i and the center wavelengthλ_(0j) of an emitter j being closest in wavelength, the respectivebandwidth Δλ_(i) of the individual emitters, and the relative outputpower A_(i) of each emitter.

FIGS. 2A and 2B depict the frequency and bandwidth characteristics ofsuitable laser light sources. Specifically, FIGS. 2A and 2B depictensemble spectra of bandwidth-enhanced laser light produced from anarray of spatially separated, discrete emitters of laser radiation. Eachemitter has a respective spectral bandwidth Δλ_(i) centered at somearbitrary red, green or blue wavelength λ_(0i). The emitters of aparticular color of laser light are designed to have slightly differentcentral wavelengths, thereby creating an ensemble bandwidth ΔΛ which isgreater than the bandwidth Δλ_(i) of any individual emitter. Byengineering the amount of ensemble bandwidth ΔΛ required for thecancellation of speckle, the quasi-monochromatic property responsiblefor the appearance of fully-saturated color is preserved. A meanspectral overlap parameter γ= Δλ_(i) / S_(i) , where Δλ_(i) is the meanspectral bandwidth of the emitters and S_(i) is the mean wavelengthshift between center wavelengths as described above, can be associatedwith the ensemble wavelength characteristic of an array of emitters of aparticular color. In a first scenario with γ>1, shown in FIG. 2A, thereexists substantial overlap in the spectra from the individual emitters(top FIG. 2A). The resulting ensemble spectrum Λ is a smoothly varyingfunction of wavelength and virtually free of any spectral features fromthe individual emitters (bottom FIG. 2A). This condition may beconsidered “ideal” for bandwidth enhancement since the spectralaveraging that occurs produces a uniformly broadened distribution forγ>>1 and a large number of emitters, thereby minimizing speckle.

For γ=1, as depicted in FIG. 2B, the ensemble spectrum Λ shown at thebottom of FIG. 2B becomes a rippled function with local maximacoincident with the central wavelengths λ_(0i) of the individualemitters. Values of γless than 1 have been found to be less efficientfor reducing speckle than values of γgreater than 1. Simulations usingFourier analysis suggest that coherent interference may be even moreeffectively suppressed with a non-uniform distribution of emitterintensities, with the possibility of eliminating speckle noisealtogether.

The light source of the invention has a few advantages over the existingtechnologies used for the backlight for a liquid crystal flat paneldisplay:

Compared to traditional cold cathode fluorescent lamps (CCFLs) orrecently available light emitting diodes (LEDs), the lasers, generallyspeaking, can provide more saturated and expanded color gamut which isfully compatible with xvYCC standard for extended color space for movingpictures. The lasers can also provide highly-polarized andwell-collimated beams which aid to increase the transmission efficiencyand/or image contrast.

However, the traditional lasers used as a light source also generateunacceptable image artifact known as speckle, and often usedde-speckling techniques or methods tend to reduce the aforementionedmerits.

The laser light source design of the invention, on the other hand,relies on the aforementioned increased spectral bandwidth of the arrayof laser emitters to reduce speckle directly at the laser source. Thisis particularly beneficial when used in combination with the liquidcrystal flat panels because these flat panel displays usually do nothave enough space (i.e. depth) to adopt the additional de-specklingoptics or devices.

In addition, the entire system's reliability, as measured in its meantime between failure (MTBF), can be improved by operating the array oflaser emitters at less than their maximum rated output power, whilestill providing the cumulative laser power required to produce neededbrightness. Accordingly, the array of lasers is expected, over time, toexhibit an inherently slower rate of performance degradation than asingle, high power laser.

Therefore, the multiple array of laser emitters design described in theinvention has an enormous advantage when used as a backlight unit for aliquid crystal flat panel display.

FIG. 3 is a schematic diagram of a laser illuminated backlight 300 for aliquid crystal flat panel display, such as the flat panel display 100 ofFIG. 1, according to an illustrative embodiment of the invention. In oneconfiguration, the backlight includes a light guide 302 surrounded alongits edges by laser assemblies 304, described further below in relationto FIGS. 5A and 5B. In one implementation, the light guide 302 includesan array of microlenses 306 formed on or molded into a forward facingsurface of the light guide. In alternative implementations, thebacklight includes a highly reflective rear reflector, such as reflector102 of FIG. 1, instead of, or in addition to, having the microlenses 306molded on or into the light guide 302.

The backlight 300 includes a polarizing film 308 to polarize lightemitted from the backlight to enable proper light modulation by theliquid crystal display to which the laser illuminated backlight 300 iscoupled. Optionally, the backlight 300 also includes a diffuser sheet310 between the light guide and the polarizing film 308 to diffuse thelight emitted from the backlight 300.

The backlight 300 can be integrated with the remainder of a standardliquid crystal flat panel display module to form a complete flat paneldisplay. For example, the backlight 300 can be coupled with an array ofliquid crystal cells controlled by an active or passive matrix backplanedisposed on a transparent substrate. The backplane and the laserassemblies are coupled to driver circuits governed by one or morecontroller circuits for controlling the intensity of the lasers and foraddressing the individual liquid crystal cells, as described furtherbelow in FIG. 6. The complete display module also includes a colorfilter film, including an array of red, green, and blue color filterscorresponding to respective liquid crystal cells, along with a secondpolarizing film, a brightness enhancing film, and a cover plate.

Referring now to FIGS. 4A-4C, the number of laser assemblies used andtheir respective positions with respect to the light guide depends onthe size of the display, the desired brightness of the display, and thelevel of color and brightness uniformity desired across the display. Forexample, in FIG. 4A, multiple laser assemblies 404 are positioned alonga single edge of a light guide 402. In another configuration, in FIG.4B, multiple laser assemblies 434 are positioned along two of the fouredges of a light guide 432. In yet another configuration, depicted inFIG. 4C, multiple laser assemblies 464 are positioned at corners of alight guide 462. In each case, an appropriate light guide can beselected to achieve a desired level of light distribution. Ideally, thebacklight should be designed to have enough numbers of laser assembliesto produce a homogenous white illumination field with uniform intensity.For instance, in a 20″ diagonal liquid crystal flat panel display with4:3 aspect ratio, 20 laser assemblies are positioned along each of theupper and lower edges of the light guide (i.e. a total of 40 laserassemblies are used) to produce well-balanced white with good brightnessuniformity. This design yields approximately one laser assembly per 2-cmseparation along the edge of the light guide. Other separation distancesand/or distributions of laser assemblies may be employed withoutdeparting from the scope of the invention. For example the separationdistance may scale in relationship to the size of the display. In oneembodiment, the scaling factor for 4:3 aspect ratio displays isdifferent than the scaling factor used in 16:9 aspect ratio displays.Spacing may also vary, and may be non-uniform in other embodiments. Forexample, fewer laser assemblies may be needed near the corner ofdisplays in which laser assemblies are positioned along the side edgesin addition to along the top and bottom edges.

FIG. 5A is a schematic diagram of a first laser assembly 500 suitablefor use as a laser assembly 304 incorporated into the laser illuminatedbacklight 300 of FIG. 3. In the laser assembly 500, individual lasersare arranged in two dimensions, for example in triangles or othergeometric arrangement. As illustrated, each laser assembly includes red(R), green (G), and blue (B) lasers. While only a single laser of eachcolor is depicted in FIG. 5A, each laser assembly 500 may include one ormultiple lasers of each color, each having a slightly different centerwavelength, as described in relation to FIG. 2, to generate an ensemblewavelength suitable for reducing speckle in a resulting image.Alternatively, the ensemble λ may be achieved by the mixing of lightfrom multiple laser assemblies within the light guide 302. In addition,due to power outputs of the different lasers used to generate eachcolor, each laser assembly 500 may not have the same number of eachcolor of laser. That is, more lasers may be required to generate thedesired light output of one color than another. Lasers of a generallysame color (e.g. red lasers with slightly different center wavelengths)may be clustered together within the assembly 500 or they may beintermixed with lasers of other colors. In some embodiments, one or morecolors can be provided by a light-emitting diode. Preferably, thenumber, ensemble wavelength, and power of the lasers are selected suchthat when the output of the lasers in all laser assemblies 500 is mixed,the result is a substantially pure white light source, which whenmodulated, yields an image substantially free of speckle.

The laser assembly 500 also includes a heat sink 502 for dissipatingheat generated by the lasers incorporated into the assembly. In oneembodiment, to promote diffusion of the laser light and proper colormixing within the light guide 302, the laser assembly includes anoptical element, such as a concave lens 504, positioned between thelasers and the light guide.

FIG. 5B is a schematic diagram of a second laser assembly 550 suitablefor use as the as a laser assembly 304 incorporated into the laserilluminated backlight 300 of FIG. 3. In the laser assembly 550,individual lasers are arranged in a linear or single dimension fashion.As illustrated, each laser assembly includes red (R), green (G), andblue (B) lasers. While only a single laser of each color is depicted inFIG. 5B, each laser assembly 550 may include one or multiple lasers ofeach color, each having a slightly different center wavelength, asdescribed in relation to FIG. 2, to generate an ensemble wavelengthsuitable for reducing speckle in a resulting image. Alternatively, theensemble λ may be achieved by the mixing of light from multiple laserassemblies within the light guide 302. In addition, due to power outputsof the different lasers used to generate each color, each laser assembly550 may not have the same number of each color of laser. That is, morelasers may be required to generate the desired light output of one colorthan another. Lasers of a generally same color (e.g. red lasers withslightly different center wavelengths) may be clustered together withinthe assembly 550 or they may be intermixed with lasers of other colors.In some embodiments, one or more colors can be provided by alight-emitting diode. Preferably, the number, ensemble wavelength, andpower of the lasers are selected such that when the output of the lasersin all laser assemblies 500 is mixed, the result is a substantially purewhite light source, which when modulated, yields an image substantiallyfree of speckle.

The laser assembly 550 also includes a heat sink 552 for dissipatingheat generated by the lasers incorporated into the assembly. In oneembodiment, to promote diffusion of the laser light and proper colormixing within the light guide 302, the laser assembly 550 includes anoptical element, such as an equilateral prism 554, positioned betweenthe lasers and the light guide 302.

FIG. 6 is a schematic diagram of a laser illuminated edge-lit backlight600 with area-dimming control for a liquid crystal flat panel display.In one illustrative configuration, the display is divided into fourregions A₁, A₂, A₃, and A₄, each with its own light guide 602 a, 602 b,602 c, and 602 d, respectively. Each region is illuminated by a row oflaser assemblies 604 a, 604 b, 604 c, and 604 d, respectively. The laserassemblies are coupled to a set of driver circuits (not shown) andcontrolled by one or more controller chips 606. Each row of laserassemblies can be controlled independently of the other rows of laserassemblies to adjust the brightness in a particular region of thedisplay. The intensity of a color within each laser assembly can also becontrolled independently of the other colors in the assembly. In oneembodiment, reflective separators or air gaps 608 are positioned betweenthe light guides 602 to facilitate independent control of the brightnessof each region of the display. In alternative configurations, thedisplay may have fewer than or more than four rows, depending on thegranularity of area dimming desired.

FIG. 7 is a schematic diagram of a laser illuminated direct litbacklight 700 for a liquid crystal flat panel display, according toanother illustrative embodiment of the invention. The backlight includesa plurality of laser assemblies 702, as described above in FIGS. 5A and5B, mounted on a highly reflective rear reflector in a rectangulararray. Each laser assembly provides light for an entire predeterminedregion of the display, without the need for scanning the laser. Thedesired field of illumination is achieved by selection of suitableoptical elements 504 in the laser assemblies.

The backlight 700 includes a polarizing film 704 to polarize lightemitted from the backlight to enable proper light modulation by theliquid crystal display to which the laser illuminated backlight 700 iscoupled. Optionally, the backlight 700 also includes a diffuser sheet706 between the light guide and the polarizing film 704 to diffuse thelight emitted from the backlight 700.

The backlight 700 can be integrated with the remainder of a standardliquid crystal flat panel display module to form a complete flat paneldisplay. For example, the backlight 700 can be coupled with an array ofliquid crystal cells controlled by an active or passive matrix backplanedisposed on a transparent substrate. The backplane and the laserassemblies are coupled to driver circuits governed by one or morecontroller circuits for controlling the intensity of the lasers indifferent regions of the display and for addressing the individualliquid crystal cells. Each laser assembly can be controlledindependently of other assemblies in the same row and column, and theintensity of a color within a laser assembly can be controlledindependently of the other colors in the assembly, similar to thedescription above in relation to FIG. 6. The complete display modulealso includes a color filter film, including an array of red, green, andblue color filters corresponding to respective liquid crystal cells,along with a second polarizing film, a brightness enhancing film, and acover plate.

While the invention has been disclosed in connection with the preferredembodiments shown and described in detail, various modifications andimprovements thereon will become readily apparent to those skilled inthe art. Accordingly, the spirit and scope of the present invention isto be limited only by the following claims.

1. A flat panel display, comprising: a backlight including a pluralityof lasing elements of at least two primary colors arranged in aplurality of laser assemblies, wherein the plurality of lasing elementsof at least one of the three primary colors are selected such that eachlasing element emits a laser beam with a center wavelength λ_(0i) and aspectral bandwidth Δλ_(i), wherein the center wavelength of at least oneof the lasing elements is wavelength-shifted with respect to the centerwavelength of at least one other lasing element, and wherein said laserbeams, when combined, have an ensemble spectrum Λ with an overlapparameter γ= Δλ_(i) / S_(i) , with Δλ_(i) being a mean spectralbandwidth of the lasing elements and S_(i) being a mean wavelength shiftbetween the center wavelengths λ_(0i) of the at least one and the atleast one other lasing elements, with Δλ_(i) and S_(i) selected suchthat γ≧1; an array of light modulators arranged across the flat paneldisplay for modulating light emitted by the backlight.
 2. The flat paneldisplay of claim 1, wherein each laser assembly includes at least onelasing element of each primary color.
 3. The flat panel display of claim1, wherein at least one laser assembly includes a plurality of lasingelements of at least one primary color.
 4. The flat panel display ofclaim 1, wherein the light modulators comprise a liquid crystal display(LCD) panel.
 5. The flat panel display of claim 1, wherein the backlightcomprises a light guide for substantially distributing light output bythe plurality of laser assemblies across the flat panel display.
 6. Theflat panel display of claim 5, comprising diffusion optics correspondingto the plurality of laser assemblies.
 7. The flat panel display of claim5, wherein the plurality of lasers are positioned about an exterior edgeof the light guide.
 8. The flat panel display of claim 7, wherein theplurality of lasers are positioned about each exterior edge of the lightguide.
 9. The flat panel display of claim 7, wherein the plurality oflasers are positioned at corners of the light guide.
 10. The flat paneldisplay of claim 7, wherein the plurality of laser assemblies arearranged about the light guide in a plurality of rows.
 11. The flatpanel display of claim 10, wherein each row of laser assemblies isconfigured for independent control with respect to laser assemblies inat least one other row.
 12. The flat panel display of claim 11, whereinthe laser assemblies are configured such that the brightness of at leastone color within at least one laser assembly can be controlledindependently of other colors in the laser assembly.
 13. The flat paneldisplay of claim 10, comprising a plurality of additional light guides,wherein each light guide corresponds to a row of laser assemblies. 14.The flat panel display of claim 13, comprising reflective separatorspositioned between the plurality of light guides.
 15. The flat paneldisplay of claim 1, wherein the plurality of laser assemblies of thebacklight are configured to directly illuminate the array of lightmodulators from behind.
 16. The flat panel display of claim 15, whereinthe laser assemblies are arranged in an array behind the array of lightmodulators.
 17. The flat panel display of claim 16, wherein each laserassembly comprises at least one lasing element of each of the at leasttwo primary colors.
 18. The flat panel display of claim 16, comprisingdiffusion optics corresponding to the plurality of laser assemblies. 19.The flat panel display of claim 16, wherein each laser assembly isconfigured to be controlled independently of at least one laser assemblyin the same row and at least one laser assembly in the same column asthe laser assembly.
 20. The flat panel display of claim 19, wherein atleast one laser assembly is configured such that the brightness of onecolor of laser is controllable independently of lasers of other colorsin the assembly.
 21. A flat panel display, comprising: a backlightincluding a plurality of lasing elements of at least two primary colorsarranged in an array of laser assemblies; an array of light modulatorsdirectly illuminated from behind by the plurality of laser assemblies; aplurality of optical elements for diffusing light from the laserassemblies across corresponding regions of the array of lightmodulators.
 22. The flat panel display of claim 21, wherein each laserassembly comprises at least one lasing element of each of the at leasttwo primary colors.
 23. The flat panel display of claim 21, wherein eachlaser assembly is configured to be controlled independently of at leastone laser assembly in the same row and at least one laser assembly inthe same column as the laser assembly.
 24. The flat panel display ofclaim 23, wherein the laser assemblies are configured such that thebrightness of at least one color within each laser assembly can becontrolled independently of other colors in the laser assembly.